1. Field of the Invention
This invention relates to the use of compounds containing polyether chains prepared by reaction of epoxidized C.sub.10-22 a carboxylic acid derivatives with polyalkylene glycols having average molecular weights of 100 to 2,000 and/or certain alkoxylated aliphatic compounds for the removal of printing inks from printed wastepaper and/or paper circuit waters.
Today, wastepaper is used in large quantities for the production of, for example, newsprint and sanitary paper. Lightness and color are important quality features for papers of this type. To achieve this, the printing inks have to be removed from the printed wastepaper. This is normally done by deinking processes essentially comprising two steps, namely:
1. disintegrating the wastepaper, i.e. fiberizing in water in the presence of the chemicals required for detachment of the printing ink particles and PA1 2. removal of the detached printing ink particles from the fiber suspension.
The second step can be carried out by washing or flotation (Ullmanns Encyclopadie der technischen Chemie, 4th Edition, Vol. 17, pages 570-571 (1979)). In flotation, which utilizes the difference in wettability between printing inks and paper fibers, air is forced or drawn through the fiber suspension. Small air bubbles attach themselves to the printing ink particles and form a froth at the surface of the water which is removed by savers.
The deinking of wastepaper is normally carried out at alkaline pH values in the presence of alkali metal hydroxides, alkali metal silicates, oxidative bleaches and surfactants at temperatures in the range from 30.degree. to 50.degree. C. Anionic and/or nonionic surfactants, for example soaps, ethoxylated fatty alcohols and/or ethoxylated alkyl phenols are mainly used as surfactants (Wochenblatt fur Papierfabrikation 17, 646 to 649 (1985)).
2. Discussion of Related Art
German patent application DE 31 01 444 relates to a process for the deinking of wastepaper using a compound corresponding to the following general formula ##STR1## in which R is a C.sub.7-21 alkyl or alkenyl group, R' is a hydrogen atom or a C.sub.1-18 alkyl, alkenyl or acyl group, AO represents C.sub.3 H.sub.6 O or C.sub.4 H.sub.8 O groups or a mixture of C.sub.2 H.sub.4 O, C.sub.3 H.sub.6 O and C.sub.4 H.sub.8 O groups, m is an integer of 1 to 100 and n is an integer of 1 to 100.
The use of ethoxylated castor oils for the deinking of printed wastepaper is known, for example, from JP 78/52705, reported in Chem. Abstr. 89, 131445j (1978), and from DE 21 48 590. The Japanese patent describes mixtures of castor oil with 10 to 400% ethylene oxide and ethoxylated nonylphenol which are suitable for the removal of printing inks from printed wastepaper. The process protected in DE-PS 21 48 590 is concerned with organic materials, for example paper, which are bleached with sodium chlorite in the presence of organic compounds containing at least one ethylene oxide and/or propylene oxide unit. Suitable organic compounds containing at least one alkylene oxide unit include inter alia ethoxylated castor oil.
However, where ethoxylated castor oils are used for removing printing inks from wastepaper, it has to be accepted that the quantities of castor oil and, hence, ethoxylated castor oils available on the market are subject to considerable fluctuations. Poor harvests in the main areas of cultivation, namely Brazil and India, result in shortages of the starting material, castor oil, at more or less long intervals. Accordingly, there is a need for a substitute for ethoxylated castor oils which, when used for the removal of printing inks from wastepaper, are at least comparable with the product to be replaced in regard to the deinking results obtained. Above all, the substitute product should be readily obtainable from a broader raw material base less vulnerable to crises and should be both ecologically and toxicologically safe.